Removal from plasma of circulating glyceride-rich endogenous very- low density lipoproteins (VLDL) is mediated by lipoprotein lipase (LPL), a pathway shared by exogenous or alimentary lipoproteins. The Framingham study has related elevated plasma VLDL concentrations to coronary risk. Therefore, we are vitally concerned with the factors which regulate plasm VLDL, and, specifically, the role of lipoprotein lipase in this process. The purpose of this work is to examine lipoprotein lipase-mediated lipoprotein removal in normal and lipemic man. To circumvent serious practical and theoretical limitations of earlier methods for LPL measurement we propose to: 1) Purify the enzyme LPL; 2) Investigate the properties of purified LPL; 3) Develop monospecific antisera against this enzyme; and 4) Use these antisera for a specific and sensitive immunoassay.